Ultimately proof is a matter of personal conviction. No one has to believe anything they do not want to believe. Simply because a certain belief is shared by many people does not prove that it is true. However, in genealogy we are not so much concerned about belief and absolute proof as we are in careful and consistently applied methods to obtain the best possible reasonably available information or "evidence." Let me start by giving an example.
I may believe that I have a pedigree that "goes back to Adam." My belief in this pedigree may also be shared by a vast number of other genealogical researchers. Does my belief constitute proof of the verity of the pedigree? My answer to this question is directed at the method by which this information was obtained. Did the claimant spend the time and effort to accumulate the information in the pedigree or did the claimant merely copy the information from some source? At which point did the research efforts of the claimant end and the copying begin? In this analysis of the issue of verity, I would focus more on the connections to the existing traditional pedigrees than in the reliability of the pedigrees themselves. For example, I do not think it is necessary for me, as a genealogist, to debate the accuracy of Biblical genealogies. Belief in the Bible is certainly a matter of personal conviction but very, very few people ever obtain the historical and linguistic background knowledge to make independent judgment of the reliability of Biblical events including the transmitted pedigrees. Even if you accept the Bible as "true" that does not validate a pedigree from the last person mentioned in the Bible down to a supposed connection with any one living individual's pedigree. Almost without exception, all of the "back to Adam" pedigrees floating around in the genealogical community rely on some form of published line of ancestry. If I choose to adopt one of those pedigrees, that is a matter of believe, but the act of accepting a published pedigree, no matter the reliability, is a question of belief and does not prove anything.
But the act of adopting a published pedigree and incorporating that information into my own pedigree without independent and "exhaustive" verification of the facts violates a basic tenet of genealogy. Now, it is true that historically, very little of the genealogical data accumulated in published genealogies was subject to anything that could be considered a rigorous examination. Further, as I said earlier, that many people believe the information contained in the published genealogies has no bearing whatsoever on the issue of proof.
So, as a genealogical community, how do we move beyond our shaky historical roots and compile some kind of credible information? Well, I think we are on our way to doing this at the core of genealogy, if we entirely disregard the millions of unsourced and unproven family trees online. Finding that core is the challenge. How do I move a fact from the unproven category to the proven category? The answer to that question lies at the heart of the integrity of the entire process of genealogy.
It is time for another hypothetical situation. Let's suppose that I am just beginning my genealogical research. One fact is a basic biological "truth." I have one biological father and one biological mother. Irrespective of the cultural, religious or social system I live in and adhere to, I still have a lattice work pedigree that consists of one male and one female ancestor at each node or juncture in the pedigree. The standard and commonly used pedigree model accurate reflect this fact. In this hypothetical I am ignoring the multitude of cultural, legal or other types of relationships that can occur, such as adoptive, surrogate, guardianship and other types of relationships that may and do exist. The existence of these alternative types of parentage do not negate the basic biological facts of our existence. Fundamentally, genealogy is the process of identifying the individuals who existed at each node in any give family tree. In other words, I am in the process of identifying my biological parents, grandparents, great-grandparents etc.
So as I begin my research, I may or may not know who my biological parents were. I may not care or I may think that identifying them is crucial to my life. Irrespective of my believe, how I go about the task of identifying them is what determines whether or not the relationship I come to believe is proved or merely conjectural. Much of what has been written about genealogical proof deals with the burden of quantifying evidence. Evidence is not proof. Evidence is evidence. At some point, genealogy and any other investigative process, such as law, science etc., must reach a common consensus that a certain amount of evidence constitutes proof. This is accomplished by judges, peer review or other processes. Where we set that level of evidence determines the rigor of the pursuit. We may form our opinion of the level of proof through documentary, circumstantial or other types of evidence but at the core of the issues regarding proof is the level or amount of evidence necessary to convince the researcher that the "fact" has been proved. Because we have no system of genealogical judges or peer review, we must rely on the cumulative genealogical community for validation. This is the flaw in the genealogical community; there is not objective review except in very limited contexts. Each family must come to its own consensus.
Looking at my hypothetical, I may believe what my parents told me about my birth and I may rely completely on a birth certificate. For my own personal purposes, that might be enough to establish my own parents. But as we move backward in time and examine individual relationships that are more and more remote from the present, this process becomes much harder to reach the same level of proof. Eventually and very soon, we move into the area where we have conflicting evidence and we must make judgment calls.
I guess I will continue with this discussion at a later date.